Phthalide

ABSTRACT

THE PHTHALIDE, 3 - (1 -ETHYL-2-METHYLINDOL-3-YL)-3-(1BENZYL-2-METHYLLINDOL-3-YL) PHTHALIDE, IS DISCLOSED. THIS PHTHALIDE IS REPRESENTED BY THE STRUCTURE:   3-(1-(C2H5-),2-CH3-INDOL-3-YL),3-(1-(PHENYL-CH2-),2-CH3-   INDOL-3-YL)PHTHALAN-1-ONE   THIS COMPOUND IS USED IN PRESSURE-SENSITIVE RECORD MATERIAL AND IN MARK-FORMING MANIFOLD SYSTEMS.

"United States Patent 3,812,146 PHTHALIDE Sheldon Farber, Appleton,Wis., and Arthur J. Wright, Dayton, Ohio, assignors to The National CashRegister Company, Dayton, Ohio No Drawing. Filed May 12, 1972, Ser. No.252,785 Int. Cl. C07d /06, 27/56 U.S. Cl. 260326.14 R 1 Claim ABSTRACTOF THE DISCLOSURE The phthalide, 3 (l ethyl-2-methylindol-3-yl)-3-(1-benzyl-2-methylindol-3-yl) phthalide, is disclosed. This phthalide isrepresented by the structure:

| N CHs This invention relates to colorless, but colorable compounds.More specifically, this invention relates to a certain phthalidecompound.

This compound is colorless or substantially colorless when in liquidsolution, but is converted to a red-colored form upon reactive contactwith an acidic material. In pressure-sensitive mark-forming systems, theunreacted mark-forming components (the colorless, but colorable compoundand the acidic material) and a liquid solvent in which each of themark-forming components is soluble is disposed on or within a sheetsupport material. The liquid solvent is present in such form that ismaintained isolated by a pressure-rupturable barrier at least one of themarkforming components until the application of pressure causes a breachof the barrier in the area delineated by the pressure pattern. Theapplication of pressure brings the mark-forming components into reactivecontact, thereby producing a distinctive mark.

Various phthalide compounds are known in the art. For example, see U.S.Pat. 3,509,174, which discloses many 3-(indol-3-yl) phthalides.

The phthalide, 3 (1 ethyl-2-rnethylindol-3-yl)-4-(lbenzyl-2-methylindol-3-yl) phthalide now has been invented. Generally,phthalide compounds have adequate solubility properties for use inpressure-sensitive record material and in mark-forming manifold systems.The phthalide of this invention has greatly increased solubilityproperties.

Accordingly, "an object of this invention is to provide a colorless, butcolorable phthalide compound.

Other objects, aspects and advantages of this invention will be apparentto one skilled in the art from the following disclosure and appendedclaim.

The colorless, but colorable phthalide of this invention is representedby the structure:

The color developed from this compound is red.

In a preferred embodiment of this invention, the phthalide and liquidsolvent are encapsulated in microscopic capsules which are coated onbase sheet record material. In close contact with the base sheet recordmaterial is a sensitized undersheet. The base sheet yields the phthalideunder pressure of writing against the sensitized undersheet in a patternof droplets corresponding to the written matter, in accordance with thedisclosure of such a capsule-bearing sheet in U.S. Pat. No. 2,712,507which issued July 5, 1955, on the application of Barrett K. Green. U.S.Pat. No. 2,712,507 also discloses a preferred method of forming thecapsules. Other preferred methods for preparing solvent-containingmicroscopic capsules are disclosed in US. Pat. No. 2,800,457 whichissued on July 23, 1957, on the application of Barrett K. Green andLowell Schleicher and in U.S. Pat. No. 3,041,289, which issued on June26, 1962, on the application of Bernard Katchem and Robert E. Miller.

The encapsulated droplets are released by the rupture of capsules inwriting operations. The phthalide liquid droplets are transferred in thepattern of the data configuration to the top of the underlying sheet.The top of the underlying sheet is coated or impregnated with at leastone material which is an acid reactant with respect to the phthalide andproduces color with any such component that is reactive therewith.Representative acidic coating materials are, on one hand, oil-insolubleminerals or inorganic particulate solid material, represented by kaolin,attapulgite, silica gel, zeolites, and the like, and, on the other hand,organic polymeric acidic materials, such as acid-reacting phenolicresins of oil-soluble characteristics.

The record member consists of a base sheet or web member either offibrous construction, such as paper, or of continuous structure, such asfilms of organic polymer material, carrying the color reactant in. anexposed state with respect to applied liquid. The acid reactant, when ofparticulate nature, is arranged in intimate juxtaposition to form anapparently unbroken liquid receptive surface, yet substantially eachparticle individually is available for contact with applied liquid.Polymeric materials of sufficient activity in an acid sense and suitablefor use in this invention because they are oil-soluble are disclosed ina continuation application for U.S. Letters Patent, Ser. No. 744,601,filed June 17, 1968, based on applications for U.S. Letters Patent Ser.No. 392,404, filed Aug. 27, 1964, by Robert E. Miller and Paul S.Phillips, Jr., both now abandoned.

Among the oil-soluble organic polymeric materials suitable for use inthis invention together with appropriate solvents to be used therewith,acid-reaction phenol-aldehyde and phenol-acetylene polymers, maleicacid-rosin resins partially or wholly hydrolyzed styrene-maleicanhydride copolymers and ethylene-maleic anhydride copolymers, carboxypolymethylene (Carbopol 934), and wholly or partially hydrolyzed vinylmethyl ether-maleic anhydride copolymer are specified as typical of thereactive acidic polymeric materials.

Among the phenol-aldehyde polymers found useful are members of the typecommonly referred to as novolaks, which are characterized by solubilityin common organic sol-vents and which are, in the absence ofcross-linking agents, permanently fusible. Another group of usefulphenol polymeric materials are alkylphenolacetylene resins, likewisesoluble in common organic solvents and possessing permanent fusibilityin the absence of being treated by cross-linking materials. Generally,the phenolic polymer materials useful in practicing this invention arecharacterized by the presence of free hydroxyl groups and by the absenceof groups, such as methylol, which tend to promote infusibility orcross-linking of the polymer, and by their solubility in organicsolvents and relative insolubility in aqueous media.

A laboratory method useful in the selection of suitable phenolic resinsis a determination of the infrared radiation absorption pattern of acandidate material. It has been found that phenolic resins showing anabsorption in the 32003500 cm. region (which is indicative of the freehydroxyl groups) and not having an absorption in the 1600-1700 cm.-region are suitable. The latter absorption region is indicative of thedesensitization of the hydroxyl groups and consequently makes suchgroups unavailable for reaction with the chromogenic material to bespecified.

The liquid solvent portion of this invention is capable of dissolvingthe mark-forming components. The solvent can be volatile or nonvolatile,and a single or multiple component solvent which is wholly or partlyvolatile can be used. Examples of volatile solvents useful with thephthalide and acidic polymer mark-forming components specified aretoluene, petroleum distillate, perchloroethylene, and xylene. Examplesof nonvolatile solvents are highboiling-point petroleum fractions andchlorinated diphenyls.

Generally, the solvent forming the vehicle to a large extent should bechosen so as to be capable of dissolving at least 1%, on a weight basis,of the phthalide, preferably in excess of 2% and a larger amount ofpolymeric matterialup to say, or moreto form an efiicient reaction.However, in the preferred system, the solvent should be capable ofdissolving an excess of the polymeric material, so as to provide everyopportunity for maximum reaction utilization of the benzopyran and thusto assure the maximum coloration at a reaction site.

A further criterion of the selected solvent is that it must notinterfere with the mark-forming reaction. In some instances, thepresence of the solvent may interfere with the mark-forming reaction ordiminish the intensity of the mark, in which case the solvent chosenshould be sufficiently vaporizable to assure its leaving the reactionsite after having, through solution, brought the markforming componentsinto intimate admixture, so that the mark-forming reaction proceeds.

In the base-acid color system, as stated above, the polymericmark-forming component(s) chosen must be acidic relative to thephthalide compound and reactive with the phthalide material to effectthe distinctive color formation or color change.

Kaolin is generally known and used in the papermaking industry as chinaclay and is outstandingly preferable as a particulate oil-insoluble andwater-insoluble mineral material of acid characteristics necessary tocolor the phthalide of this invention. A white kaolin is used, and,because of its whiteness, its plate-like particle form, which gives itunparallel coating properties in aqueous slurries, its universalabundance in supply, its historical general usage in the papermakingandpaper-converting industries, and its low cost, it is an idealmaterial. Other types of particulate and substantially colorlesswaterand oil-insoluble minerals of the necessary acid properties aredeemed equivalents of kaolin, some being bentonites.

Attapulgite can be used in this invention as an efiicient colorlessmineral reactant material to color the phthalide of this invention thatreact on contact in an electrondonor-acceptor reaction, and, by reasonof its high oil absorbency, is doubly useful as an absorbent reactantcoating on paper to form color with such compounds dissolved in oil asmay be applied to it.

Various methods known to the prior art and disclosed in theaforementioned application Serial No. 392,404 to Miller, et al. and US.Pat. No. 3,455,721, issued July 15, 1969, can be employed in coatingcompositions of the mark-forming materials into their supporting sheets.An example of the compositions which can be coated onto the surface ofan underlying sheet of a two-sheet system to react with the capsulecoating of the underside of an overlying sheet is as follows:

Coating composition: Percent by weight Phenolic polymer mixture 17 Papercoating kaolin (white) 57 Calcium carbonate 12 Styrene butadiene latex 4Ethylated starch 8 Gum arabic 2 The advantages of this invention arefurther illustrated by the following examples. The reactants and theproportions and other specific conditions are presented as being typicaland should not be construed to limit the invention unduly.

EXAMPLE I Preparation of 3-(l-benzyl-2-methylindol-3-yl)-3-(lethyl-2-methylindol-3 -yl) -phthalide A mixture of 9.26 g. (0.03 moles)of I-ethyI-Z-methyl- 3-(2-carboxybenzoyl) indole, 6.63 g. (0.03 moles)of 1- benzyl-Z-methyl indole and 90 ml. of acetic anhydride were heatedon a steam bath for two and one half hours. The reaction mixture waspoured into ice water and made basic with ammonium hydroxide to a pH of8-9. Additional cooling was necessary. The aqueous solution wasextracted with benzene and the benzene washed three times with 5% sodiumhydroxide solution and then with water until neutral. The benzene wasdried (Na SO concentrated and diluted with petroleum ether. Thesupernatant was decanted and the oil was washed with petroleum ether anddissolved in acetonitrile. After standing overnight, 4.0 g. (28%) ofmaterial was filtered, M.P. -7 C. The material was characterized byelemental analyses after repeated recrystallization. Calcd. for C H N 0C, 82.33; H, 5.92; N, 5.49. Found: C, 82.13; H, 6.07; N, 5.54. A benzenesolution of this compound when applied to paper coated with clay orphenolics gave a red color.

EXAMPLE II The 3-(1-ethy1 2 methylindol-3-yl)-3-(1-benzyl-2-methylindol-3-yl) phthalide prepared in Example I and two otherphthalides, 3,3-bis(1-ethy1-2-methylindol-3-yl) phthalide and 3,3-bis(l-benzyl 2 methylindol-3-yl) phthalide, each were individuallydissolved in a 2:1 mixture by weight of monoisopropylbiphenyl andmagnaflux oil. Each solution was saturated with the respectivephthalide. After one Week, the solution of the inventive phthalidecontained about 2% of the inventive phthalide and the solutions of theother phthalides contained about 0.2 and 0.1% of the respectivephthalide. These results demonstrate that the phthalide of thisinvention has greatly increased solubility properties over knownphthalides.

Although this invention has been described in considerable detail, itmust be understood that such detail is for the purposes of illustrationonly and that many variations and modifications can be made by oneskilled in the art without departing from the scope and spirit thereof.

What is claimed is:

1. 3-(1 ethyl-2-methylindol-3-yl)-3-(l-benzyl-Z-methylindol-3-yl)phthalide.

Lin 260326.l4

5 JOSEPH A. NARCAVAGE, Primary Examiner US. Cl. X.R.

